Method and apparatus for protecting drainage pipe installed underground

ABSTRACT

A pipe protection apparatus includes a sheet of permeable material having an inner surface and an outer surface and a longitudinal direction and a width direction defined by two edges of the sheet along the longitudinal direction. A fastening structure is configured to join the two edges to form a seam as the sheet of permeable material is wrapped in the width direction around a drain pipe configured to be installed underground to form a sock along the longitudinal direction. The sock is configured to be installed underground with the drain pipe about which it is wrapped, yet to remain for a service life in non-bonding contact with the pipe.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. provisionalpatent application Ser. No. 61/650,832, METHOD AND APPARATUS FORPROTECTING PIPE INSTALLED UNDERGROUND AFTER HORIZONTAL DRILLING, filedMay 23, 2012, and co-pending U.S. patent application Ser. No.13/787,222, METHOD AND APPARATUS FOR PROTECTING PIPE INSTALLEDUNDERGROUND, filed Mar. 6, 2013, which applications are incorporatedherein by reference in their entirety. This application is also relatedto U.S. patent application Ser. No. 13/787,359, COUPLER METHOD ANDAPPARATUS FOR INSTALLING PIPE WITH A PROTECTIVE COVER INTO BOREHOLE,filed Mar. 6, 2013, which application is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The invention relates to a method and apparatus for protecting pipeinstalled underground and more particularly to drainage pipe installedin a borehole or existing host pipe or conduit.

BACKGROUND OF THE INVENTION

Directional drilling (also referred to in the art as “horizontaldrilling” or “horizontal directional drilling”) was invented in the1920s and the technology was originally used in oil fields to increaseoil production. In the 1990s, directional drilling technology wasadapted for utility installations. Directional bores have been installedfor pipelines carrying oil, natural gas, petrochemicals, water, sewage,and other products. Also, directionally drilled holes have been used toinstall conduits which carry electric and fiber optic cables. Suchcontinuous pipes, conduits, casings and the like are referred tohereinafter generally as “pipe”.

Besides crossing under highways, railroads, airport runways, shoreapproaches, traffic islands, and areas congested with buildings,directionally drilled installations have been made under rivers andwaterways, pipeline corridors, and protected wetlands. Directionalborings have the least environmental impact of any alternateconstruction method. Directional drilling technology also allowsplacement of pipe under obstacles, provides maximum protection for theinstallation, and minimizes maintenance costs. During installation,normal business operations are usually not interrupted. Directionalborings also have a predictable and short construction schedule.

Typically, after a directional boring pass is complete, a permanent pipe(e.g. a gas pipe, conduit, or casing of some sort) is pulled or pushedthrough the boring also known as a borehole. In the prior art, the pipe,which may be formed of, for example, metal or plastic, is notnecessarily provided with exterior chafe protection prior to beinginserted into the boring and thus, the pipe and any pipe coatings arevulnerable to damage from contact with protruding rocks and the like.

Many utility distribution piping systems are buried undergroundthroughout the world. Older piping systems were often formed of castiron or bare steel pipe. Newer systems may include coated steel orpolyethylene. Older systems may also tend to be in urban or congestedareas under asphalt or concrete paving that would render the replacingor rehabilitating such pipes expensive and disruptive to surfaceactivities. Sliplining or host pipe insertion has also been used as amethod for rehabilitation of existing pipelines to repair leaks orrestore structural stability. Sliplining is completed by installing asmaller, “carrier pipe” into a larger “host pipe.” The carrier pipe maybe continuous along an entire run of pipeline or consist of multiplesegments of pipe that are joined or fused end to end. Common materialused to slipline an existing pipe include high density polyethylene(HDPE), fiberglass reinforced pipe and poly vinyl chloride (PVC). A hostpipe may include debris, slag, burrs or sharp internal edges betweenpipe segments, as well as internal projections or coupons at serviceconnection fittings that may damage or score the external surface of thecarrier pipe as it is inserted within the host pipe.

As described in CA Patent No. 2517980C, hoses have been used asprotective sleeves for borehole pipe installation. However, suchrelatively flexible materials, such as fire hoses, polyester materials,and other relatively loose weave materials, are water absorbent and canbe difficult to install once water logged. Also, post-installationingress of water and other ground contaminants such as petrochemicalscause pipe corrosion and/or degradation and in some cases premature pipefailure. Hoses can also be difficult and time consuming to pull overpipes being prepared into pipe-hose assemblies for installation into theborehole. Post-installation, such hoses can be subject to undesirablepermanent bonding between the pipe, the hose, and the surrounding soilmatrix.

Another problem involves the installation of drainage systems thattypically utilize perforated pipe having relatively fragile structuralintegrity. Many drain pipes have relatively thin walls or porous wallstructures which can be easily damaged during installation. At least inpart because some drain pipes are relatively fragile and/or susceptibleto debris entering drain holes during installation, it is common fordrain pipes to be installed using open trench techniques. Where drainpipe is pulled or pushed into an existing hole, such as a borehole,debris such as earth and small rocks can be forced into openings of thedrain pipe. One technique of the prior art allows drain pipes to beinstalled into boreholes using a multi-step procedure. The drain pipe istemporarily encased within a more robust outer pipe made from, forexample, lengths of high density polyethylene (HDPE) pipe. The drainpipe is protected during installation by the HDPE pipe. The HDPE—drainpipe assembly is first pulled into the borehole, and then the protectiveHDPE pipe is pulled out from the borehole, while the installed drainpipe is kept in place, for example, by use of a cord system.

SUMMARY OF THE INVENTION

There is a need for a more cost efficient and simpler method andapparatus for installing drain pipe.

According to one aspect, the invention features a drain pipe protectionapparatus which includes a sheet of permeable material having an innersurface and an outer surface and a longitudinal direction and a widthdirection defined by two edges of the sheet along the longitudinaldirection. A fastening structure is configured to join the two edges toform a seam as the sheet of permeable material is wrapped in the widthdirection around a drain pipe configured to be installed underground toform a sock along the longitudinal direction. The sock is configured tobe installed underground with the drain pipe about which it is wrapped.

In one embodiment, the drain pipe is configured to be installed into aborehole formed by a method selected from the group consisting ofdirectional drilling, auger boring, pipe ramming, static plowing, andcombinations thereof.

In another embodiment, the pipe protection apparatus is configured to beinserted into a host drain pipe.

In yet another embodiment, the sheet of permeable material includes along chain polyethylene.

In yet another embodiment, the sheet of permeable material includes anultra-high density polyethylene.

In yet another embodiment, the sheet of permeable material includes anaramid.

In yet another embodiment, the sheet of permeable material includes aliquid crystal polymer.

In yet another embodiment, the sheet of permeable material includes acombination of one or more materials selected from the group consistingof a long chain polyethylene, an ultra-high density polyethylene, anaramid, and a liquid crystal polymer.

In yet another embodiment, the sheet of permeable material includes awoven polypropylene loaded with carbon.

In yet another embodiment, the fastening structure includes ahook-and-loop fastener.

In yet another embodiment, the fastening structure includes a zipper.

In yet another embodiment, the permeable material includes a highstrength yarn.

In yet another embodiment, the permeable material includes a yarn formedfrom fibers having a tensile modulus equal to or greater than 150grams/denier.

In yet another embodiment, the pipe protection apparatus furtherincludes a tracer wire.

In yet another embodiment, the tracer wire is disposed within thefastener structure.

According to another aspect, the invention features a method forprotecting a drain pipe before, during and after installation, includingthe steps of: providing a sheet of permeable sock fabric; installing thesheet of permeable sock fabric around the pipe by the steps of: placingthe sheet of permeable sock fabric adjacent the drain pipe; wrapping thesheet of permeable sock fabric around the drain pipe; securing the sheetto itself along a seam to form a permeable sock-covered drain pipe; andinstalling the permeable sock-covered drain pipe underground.

In one embodiment, the step of installing the permeable sock-coveredpipe underground further includes inserting the permeable sock-coveredpipe into a borehole.

In another embodiment, the borehole is formed by a method selected fromthe group consisting of directional drilling, auger boring, piperamming, static plowing, and combinations thereof.

In yet another embodiment, the step of installing the permeablesock-covered drain pipe underground further includes inserting thepermeable sock-covered drain pipe into a host drain pipe.

In yet another embodiment, the step of providing a sheet of permeablesock fabric includes providing a roll of sheet of permeable sock fabric.

In yet another embodiment, the step of providing a sheet of permeablesock fabric includes providing a sheet of permeable sock fabricincluding a material selected from the group consisting of a long chainpolyethylene, an ultra-high density polyethylene, an aramid, a liquidcrystal polymer, and combinations thereof.

The foregoing and other objects, aspects, features, and advantages ofthe invention will become more apparent from the following descriptionand from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the invention can be better understood withreference to the drawings described below, and the claims. The drawingsare not necessarily to scale, emphasis instead generally being placedupon illustrating the principles of the invention. In the drawings, likenumerals are used to indicate like parts throughout the various views.

FIG. 1 shows an illustration of two exemplary short cut-off sections ofpipes which are partially covered by a protective sock;

FIG. 2 shows an illustration of one exemplary installation of a sock andpipe assembly into a borehole;

FIG. 3 shows an illustration of the installation of the sock-coveredpipe of FIG. 2;

FIG. 4 shows another illustration of an exemplary sock-pipe assemblyinstallation;

FIG. 5 shows a cross-section of another exemplary installation of aprotective sock around a carrier pipe within a host pipe; and

FIG. 6 shows an illustration of an exemplary fluid permeable sockcovering a drain pipe.

DETAILED DESCRIPTION

As described hereinabove, protection methods of the prior art for pipeinsertion into boreholes and host pipes have a number of problems.Although directional drilling for a pipe installation can be useful andadvantageous in many applications, directional drilling suffers fromdrawbacks. For example pipes installed following directional drillingcan be exposed to lateral hazards such as projecting rocks as well assubjected to longitudinal scraping, chafing of the pipe exterior againstprojecting rocks due to thermal cycles, or subterranean erosion duringthe working life of the installation. Scratching or chafing can damageor partially remove protective coatings on the exterior of the pipe. Insevere cases, the structural integrity of the pipe wall can becompromised. In worst case scenarios, such as, for example,polyethylene, fusible PVC, or similar type pipes carrying natural gas,the consequence of catastrophic pipe failure can include loss of lifeand property.

Host pipe insertion suffers from similar problems. For example carrierpipes installed within an existing host pipe can be exposed to lateralhazards such as burrs or sharp edges from host pipe joints, slag, debrisor projections from existing or discontinued service connections thatmay cause longitudinal scraping, chafing of the exterior of the carrierpipe. Scratching or chafing can damage or partially remove protectivecoatings on the exterior of the pipe or compromise the structuralintegrity of the carrier pipe.

In an attempt to mitigate such drawbacks, protective sheathes have beenused in the prior art. Such sheathes have been manufactured ascontinuous hoses. Therefore, prior art techniques typically requirehoses made from a somewhat flexible material, so that the hoses can thenbe pulled over a pipe to be installed into a borehole. Strongermaterials, which in many cases are substantially inflexible, are notsuitable for use with the prior art methods. It can be very difficult,if not impossible, to insert a pipe to be protected into an alreadyformed hose structure made of such inflexible materials. Also, it maynot be possible or practical to pre-form some relatively inflexiblehigh-strength materials into a pre-made hose.

Another problem with prior art hoses is that the hoses are typicallymade of materials which absorb water. Water is either absorbed directlyinto a covering fabric and/or into the spaces of the fabric weave,especially in the case of polyester fabrics. Most underground boreholesare drilled using drilling slurry, some of which remains in theborehole, and ground water and/or run-off water typically entersborehole during and after drilling. One problem with slurry and/or waterabsorption by a pipe protective cover is a significant increase inweight of the pipe/protection layer assembly. As more force is needed topull such a water/liquid logged assembly and more mass is being pulledalong sharp rocks along a borehole, damage can occur both to the pullingequipment as well as to the pipe assembly. Another problem with thewater absorption of the prior art methods is that ground water istypically contaminated by either man made contaminants and/or naturallyoccurring substances such as petrochemical pollution products andnaturally found petrochemicals. After installation of a prior art hose,there can be a continuous wicking of harmful contaminants directly tothe outside surface of the underground pipe. Over long periods of time,such contaminants can cause a relatively rapid corrosion of metal pipesand plastic/polyethylene pipes can deteriorate and weaken. In thecontinuous presence of contaminants, a portion of a plastic/poly pipecan ultimately soften or dissolve creating a fluid or gas breach in asection of an underground pipe. As such, a protective pipe-hose assemblymade with a liquid absorbent and/or permeable hose material of the priorart can actually suffer a reduction in the service life.

Turning now to the inventive method and apparatus, a solution to thewater and/or contaminant problems associated with the installation ofprotected pipes into boreholes or existing host pipes uses one or morelayers of a medium to high strength materials such as, for example, along chain a polyethylene, an ultra-high density polyethylene, aramids,liquid crystal polymers, and suitable combinations thereof. Suchmaterials can be made substantially impermeable to water as well asother typical underground contaminants. However, as describedhereinabove, some of these materials are generally less suitable formanufacture into pre-formed hoses, such as were used in the prior art.Also, even where such materials can be made into continuous hoses ortubes, pre-formed hoses or tubes would be difficult if not impossible toinstall over lengths of pipe because one or more layers of sheets madefrom these materials are substantially inflexible.

FIG. 1 shows two exemplary short cut-off sections of protected pipeswhich are partially covered by a protective material to illustrate anexemplary embodiment of a protective cover (referred to hereinbelow as a“sock”). Sock 12, a pipe protection apparatus, includes a sleeve havingan outer surface 14 and an inner surface 16. Sock 12 is formed from alength of material (e.g. a woven fabric) having a width in a widthdirection perpendicular to a longer longitudinal, length direction. Thesheet of material (e.g. a sheet of sock fabric) can be convenientlyprovided as a roll 41 (e.g. roll of sheet of sock fabric). A sock fabricof any suitable width dimension can also be provided on a bobbin, suchas, for example, an industrial bobbin, or on any other suitable form.Also, a relatively light weight sock fabric can be carried to aninstallation site as a loose roll or in any suitable fold (e.g. anaccordion fold).

Installation of a sock onto a pipe: During installation of sock 12 ontopipe 01, the length of material can be manually or machine rolled in itsshort direction (i.e. the width dimension, perpendicular to thelongitudinal direction) to substantially wrap around to conform in anon-bonding way to the diameter of the pipe to be protected. A seam 18is closed as the sock is formed in the longitudinal direction.Typically, sock 12 can be conveniently manually formed by hand. However,in some installations, there could also be an automated, semi-automated,or tool assisted installation of a sock onto a pipe by machine. In manyinstallations, roll 41 can provide enough material for a singlecontinuous sock. However, there can also be multiple joined socks 12along the length of a pipe.

Sock 12 is not permanently bonded to the pipe 01. Thus, after assemblyand installation, at least in part because of the low coefficient offriction of the sock material, sock 12 advantageously remains in slidingengagement with pipe 01. As described in more detail hereinbelow, suchloose construction allows for mechanical slippage between the pipe andsock 12 (e.g. to allow for such factors as expansion and contraction ofthe pipe and any attached pipe fittings). Sliding engagement betweenpipe 01 and sock 12 also helps to prevent the assembly of sock 12 andpipe 01 from aging into a single bonded structure. In someinstallations, again because the low coefficient of friction of sock 12,there can also be permanent non-bonded contact between the sock and thesurrounding soil matrix.

Sock seams: Seam 18 can be formed using any suitable fasteningstructure. In the exemplary installation of FIG. 1, seam 18 is formedfrom a hook-and-loop closure system including strips of hook 20 andstrips of loop 22 fastener strips. In most embodiments, the location ofthe hooks and loops on the respective sheet edges is unimportant and canbe reversed. The strips of hook 20 and strips of loop 22 fastener stripsare affixed by any suitable method, such as by sewing with industrialmethods know in the art, to the respective opposed two edges of thesheet of fabric which forms sock 12. Such fastening strips arecommercially available and widely known, for example, under the tradenames VELCRO™ and VEL-LOC™. While the embodiment of FIG. 1 as describedhereinabove used a hook-and-loop fastening technology, any suitablefastener technology can be used in place of the hook 20 and loop 22fastener strips to form the seam 18. Alternative fasteners may includeinterlocking edge fasteners, interlocking tabs, sliding edge fasteners,zippers, straps, buckles and snaps. Other methods of fastening mayinclude pressure sensitive adhesives, heat activated adhesives, solventactivated adhesives, and tapes utilizing such adhesives.

Typically, a sock 12 is provided as one continuous rolled sheet (e.g.roll 41 of material, FIG. 1). However, where more than one length ofsock 12 is used, once sock 12 has been fitted over pipe 01, the ends ofsock 12 are connected to adjacent socks if sock 12 is being applied indiscrete lengths.

Sliding engagement: As discussed hereinabove, unlike many prior artprotective pipe wrappings, while the present sock can fit snugly aboutthe pipe, sock 12 is not permanently bonded to the pipe and thus canaccommodate longitudinal shifting of the pipe within the borehole. Suchsliding engagement helps to prevent scuffing of the pipe against theborehole sidewalls. According the inventive method, a sock 12 isinstalled onto a pipe 01 without being permanently attached thereto.With such freedom of pipe movement, cohesive bonding between thesurrounding soil matrix (earth) and the pipe can be substantiallyeliminated. That is, sock 12 can remain slidingly engaged (non-bonded tothe earth) within sock 12 for the useful borehole installed service lifeof the pipe.

Installation of the pipe-sock assembly: The pipe of a pipe-sock assemblycan be attached to any suitable apparatus for emplacing the pipe andsock into a previously drilled hole. The apparatus typically inserts thepipe and sock into the borehole or existing host pipe together. When thepipe is properly positioned within the hole, the apparatus can then bedisconnected from the pipe and the sock leaving the installed pipecovered by sock 12 in the hole and ready for service.

FIG. 2 shows an illustration of one exemplary installation of a sock 12into a borehole (lower left, not shown). Arrow 99 represents thedirection of travel of pipe 01 and sock 12 into the borehole. Coupler100 holds sock 12 to pipe 01 as the assembly of sock 12 and pipe 01 ispulled into the borehole. Typically, the apparatus to install thepipe-sock assembly (e.g. a pull-head) is affixed to pipe 01 and not tothe coupler 100, which is located a distance from the end of the pipe01. A suitable such coupler and a method of installation are describedin co-pending U.S. patent application Ser. No. 13/787,359, COUPLERMETHOD AND APPARATUS FOR INSTALLING PIPE WITH SOCK INTO BOREHOLE, whichapplication is incorporated herein by reference in its entirety for allpurposes. Also visible are tracer wires 125, electrical conductors usedpost-installation for remote sensing of the location of the undergroundpipe. Seam 18 (FIG. 1) is not visible in FIG. 2. Any suitable apparatus(e.g. an apparatus including a pipe pull head) as known to those skilledin the art can be used to insert pipe 01 and a sock 12 into a borehole.In the exemplary installation of FIG. 2, coupler 100 is mechanicallycoupled by frictional forces to both pipe 01 and to sock 12. In thisembodiment, coupler 100 rides into the borehole along with pipe 01,however the installation apparatus is not directly connected to eithercoupler 100 or sock 12. Once installed in-place in the borehole,re-usable coupler 100 is typically removed from the pipe-sock assembly.

FIG. 3 shows another illustration of the exemplary installation of asock-covered pipe into a borehole of FIG. 2. Sock 12 is being formed(center top) by closing a VELCRO™ strip (loops 22 and hooks 20) to formseam 18 about pipe 01. In the foreground (lower center) the pipe can beseen as placed on the inner surface 16 of the sock fabric which is tobecome sock 12. A tracer wire 125 can also be seen in the foreground.

FIG. 4 shows illustration of an exemplary installation of a sock 12 intoa borehole. In the illustration of FIG. 4, sock 12 has already beenfitted about a pipe 01 and the seam 18 (not visible in FIG. 4) has beenformed and closed. The length of sock 12 is sufficient to cover theportion of pipe 01 that will remain in the borehole after insertion byany suitable insertion means.

FIG. 5 shows a cross-section of another aspect of the invention whereina protective sock 12 has been fitted about a carrier pipe 01 whichtogether have been installed within a host pipe 03. The protective sockprotects the carrier pipe before during and after host pipe insertionfrom lateral scraping and damage caused by debris 31, lateral serviceconnections 33 and burrs or sharp interior edges 35 at pipe joints ordamaged walls of the host pipe.

Sock materials: A fabric suitable for use to form the abrasion-resistantand cut-resistant protective cover sock can be woven from high-strengthyarns. As used herein, “high strength yarns” include, but are notlimited to, yarns formed from fibers having a nominal modulus equal toor greater than 900 grams/denier and a tenacity equal to or greater than30 grams/denier. The yarns used to form a woven sheet can be formed fromlong chain polyethylene fibers available from suppliers. For example, inone embodiment, UHMW-PE woven fabric sold under the trade name SupremeProtector™ 509WE (available from JHRG Manufacturing LLC of Spring Hope,N.C.) can be used to manufacture a sock 12. Such materials can beprovided with a thickness of about 0.020 inches (0.508 mm) and a weightof about 12.5 ounce/yard (385 grams/meter). The 509WE material has atensile strength of about 30.5 grams/denier, a modulus of about 920g/denier and a Tabor abrasion resistance of about 63,000 cycles. Asdescribed hereinabove, other suitable yarns can be formed from anultrahigh molecular weight polyethylene, aramids, or liquid crystalpolymers or combinations thereof. Fabric so formed, typically from afiber with a nominal tensile strength of more than about 10 gram/denier,has a high level of tear-resistance, abrasion-resistance,cut-and-puncture resistance, a low coefficient of friction, resistanceto low temperatures, and resistance to chemicals. For the harshestborehole environments, sock 12 can have one or more additional layersand/or coatings. Additional layers can be made from the same materials,other materials, or any other suitable fabric, or additional protectivecoating.

Materials which are slightly less robust than Supreme Protector™ 509WEare also believed to be suitable for use in harsh environments, such asa material having the following material characteristics: yarns formedfrom fibers having a tensile modulus equal to or greater than 150grams/denier and a tenacity equal to or greater than 7 grams/denier, atensile strength of 25.2 g/denier, a modulus of 785 g/denier.

In one exemplary embodiment, a 0.02″ thick sock weighs 11.5 ounces/yardand having a 1,100 pound/square inch break strength (15 times strongerthan steel), that operates normally in an ambient temperature range of−40° F. to 250° F. (i.e. for usability in the environment prior to andduring installation), is chemical resistant and provides resistance toUV radiation. UV radiation damage resistance can provide a longer shelflife prior to installation, particularly where sock materials areexposed to direct or indirect sunlight prior to installation.

In some less demanding applications, it is contemplated that arelatively low cost sock can be manufactured from medium to highstrength yarns, such as for example, a woven polypropylene loaded withcarbon with a high tensile strength and UV resistant. For example, someMauritzon Trampoline Fabrics are contemplated as suitable materials formanufacturing a sock 12 (available from Mauritzon, Inc. of Chicago,Ill.). Another fabric that is contemplated as suitable for manufacturinga slightly lighter duty a sock 12 is the TenCate Permatron® TrampolineFabric (available from TenCate Geosynthetics of Pendergrass, Ga.).

Sock Fasteners: Any suitable industrial or high strength fasteningsystem can be used to form the sock seam, such as the seam 18 of FIG. 1.In one exemplary embodiment, Velcro™ fastener strips can be attached tothe inner surface 16 and the outer surface 14 of a sock 12. For example,Velcro™ fastener strips can be attached to a sock by sewing machine witha medium to high strength thread using industrial sewing methods asknown in the art. Any other suitable hook and eye type fastening stripscan be used as loops 22 and hooks 20 to form the seam of a sock formedabout a pipe. As discussed hereinabove, where loops and hook are used,the order of loops 22 and hooks 20 is unimportant to either edge of thesock fabric and can be reversed. Recent innovations known as militarygrade hook and eye fasteners are also contemplated to be particularlysuitable for such use.

The width of either or both fastening strips can be substantially thesame, however more commonly the width of at least one strip can be madewider than the other to allow for some adjustment of the diameter of theinstalled sock. For example, referring back to FIG. 1, in someembodiments, the width of the strip of loops 22 can be made wider thanthe width of the strip of hooks 20. Also, where one or more rolls havinga width more narrow than a desired width are available, it iscontemplated that a larger diameter sock could be made in the field byassembling two or more rolls 41 together widthwise, resulting in acompleted sock having more than one seam 18.

Seam 18, typically formed in the field prior to or during installationof a pipe-sock assembly into the borehole, is not limited to hook andeye fasteners and can be accomplished using any suitable method to jointhe two longitudinal edges of the material. For example, it iscontemplated that some industrial zippers can be used to create a seam18. Depending on the fastener technology, the fastener strips can be ofany suitable type fastener which otherwise positively engages and locksthe two strips together. It is also contemplated that there could besuitable fast curing glues or adhesives which may also be suitable forfield installation of a seam 18. In the case of a fast curing glue oradhesive, in some embodiments, the glue or adhesive may be directlyapplied in strips or stripes along the edges of the inner surface 16 andouter surface 14 without need for strips of additional material.

Water-tight seams: In some applications, seam 18 can be madesubstantially water-tight to prevent liquids from seeping from theoutside soil matrix surrounding an installed sock 12, in towards theinner surface 16 of sock 12. In the most demanding applications, it iscontemplated that a seal can be added at or near seam 18. For example, agasket can be formed from one or two piece strips disposed on or near aloops 22 fastener strip. Any suitable sealing method can be used.Suitable gaskets include simple rubber strips, tongue and groovestructures which positively engage during the formation of a seam 18, aswell as additional water-resistant or water-proofing layers which cancover part of, or the entire inner surface 16 of a sock 12.

Tracer Wires: When installing a non-metallic pipe, such as for example,the yellow polyethylene pipe typically used in gas distribution systems,generally a tracer wire 125, FIG. 2, FIG. 3, is installed alongside pipe01. Then, post-installation, the location of the underground pipe can beconveniently found using electronic remote sensing techniques well knownin the art. It is contemplated that a tracer wire 125 can be furtherprotected by installation between a pipe 01 and a sock 12 (i.e. withinthe sock). A tracer wire 125 can also be placed under either fasteningstrip before the fastener strip is attached (e.g. sewed) to the materialof the sock. In such cases, tracer wire 125 can arrive at aninstallation site as an integral part of the roll 41, already assembledinto the sock. Alternately, a tracer wire 125 can be provided asprotected by its own strip affixed to the inner or outer surface of sock12. In an alternative embodiment, where the fastener is comprised ofconductive material, such as a metallic zipper or conductive thread orwire within the backing of the hook and loop fastener, the fasteneritself may be sufficient to perform the function of acting as a tracerwire.

Cathodic protection: While in some applications as describedhereinabove, a sock 12 can be made to be more water-tight or evensubstantially water-proof, in other applications, some intentionalpost-seepage of water can be advantageous. For example, some metallicpipe installations (e.g. some iron and steel pipe installations) can betreated by an electrical cathodic process to inhibit corrosion. Suchtechniques are well known in the art and analogous to similar electricalanti-corrosion techniques used to protect metallic vessel hulls in navalarchitecture. Where a cathodic anti-corrosion process is planned formetallic pipe installation into boreholes, it can still be desirable formany of the aforementioned reasons, such as protection from rock edges,to add a protective sock. However, for the cathodic anti-corrosiontechnique to operate as planned, there generally needs to be some wateringress towards the outer surface of the pipe to form a useableelectrical circuit. In such cases, sock 12 can intentionally be madesomewhat water permeable by providing small openings such as small holesto allow ground water to pass from outer surface 14 to inner surface 16post-installation. Any suitable sized opening holes can be used.Typically such holes can be relatively small, such as, for example, anarray of pin-hole sized holes, so that sock 12 does not catch or hang onany physical obstructions or sharp or jagged edges in the soil matrixduring installation into the borehole.

Drain Pipe Installation

Installation of drain pipes is problematic. Drain pipes, such as forexample, drain pipes used in French drain systems, can be somewhatfragile due to relatively thin walls and/or the perforations in the pipewalls which serve as drain holes. Also, some specialized drain pipesystems can have multiple layers of drain pipe structure, some partsmore fragile than others. Even where installation related drain pipedamage is less of a problem, it can be difficult to keep foreign matterout of the drain holes before, during, and after installation.

Drain pipes are traditionally installed by open trench digging at leastin part because setting the relatively fragile pipes into an open trenchhelps to minimize installation damage to the drain pipe. However, trenchdigging is expensive and can be disruptive to normal activities nearwhere the drain pipe is being installed.

A more recent prior art system to install drain pipe into a boreholeuses a multi-step approach. As described hereinabove, the fragile drainpipe is encased in a more robust pipe such as a HDPE pipe. The drainpipe is then protected during installation by the HDPE pipe. TheHDPE—drain pipe assembly is pulled into the borehole, and finally theprotective HDPE pipe is pulled out of the borehole while the fragilepipe is kept in place as installed in the borehole, for example, by acord system. This multi-step approach is time consuming, expensive, andrelatively inefficient.

However, constructing underground drains by techniques such ashorizontal directional drilling (HDD) can be particularly advantageous,such as, for example, in the environmental remediation industry. Suchdrain systems are commonly installed to help remediate contamination ofthe earth such as, for example, contamination by petro chemicals, fuelspills, coal ash, landfill run off and the like. Use of HDD and/orsimilar suitable installation methods to build such drain systemseliminates the need for open trenching which would otherwise disturb,expose and potentially release such toxins from an area of which theyare currently contained (underground) and therefore pose less threat ofhuman exposure.

The HDPE temporary outer protective outer casing solution describedhereinabove is believed to be particularly unsuitable in contaminationsituations because the final step of removing the temporary protectiveHDPE pipe would unnecessarily extract contaminants along with the HDPEprotective pipe from the borehole. In a worst case situation, thecontaminated HDPE pipe itself, might need to be cleaned using specialcleaning techniques and/or disposed of as hazardous waste.

It was realized that similar base materials and techniques as previouslydescribed hereinabove as impenetrable or very slightly penetrable (e.g.for cathodic treatment applications) sock, can also be made and used ina new way to solve the problem of installing drain pipe underground,such as into boreholes. In a first embodiment, the fabric of the sock asdescribed hereinabove is provided with a porous weave. The porous weaveis opposite to the sock previously described herein above, where it wasgenerally desirable to provide an impenetrable sock material. Suchintentionally penetrable fabrics, for example, would not be coated by awater proofing polyethylene coating. Where yet higher fluid drain ratesare needed, the sock fabric can be further intentionally perforated tocause openings to allow relatively high fluid flow rates.

FIG. 6 shows an illustration of one exemplary fluid permeable sock 501covering a drain pipe 502 which can be made from any pipe suitable forborehole insertion, such as for example, HDPE or MDPE pipe. The porosityrate of the fluid permeable sock 501 can be adjusted for particulardrainage applications. The pipe suitable for borehole insertion can beused as drain pipe by providing a plurality of openings, such asopenings or holes in the pipe (e.g. perforations 503). Perforations,such as perforations 503 can be either pre-made or created in the fieldoptionally using custom sizes and/or shapes suitable for a particulardrainage application. Any suitable opening or hole shape, size, andspacing between openings and/or holes can be used. Any suitablemanufacturing apparatus and/or manufacturing technique can be used tomake the holes and/or openings in the pipe. It is unimportant whetherthe openings are placed at a regular, irregular spacing or combinationthereof. As described hereinabove, permeable sock 501 can be closed overa drain pipe 502 using any suitable means, such as, for example, aVelcro closure at a seam 18.

Drain pipe suitable for borehole installation covered by a fluidpermeable sock provides significant advantages over drain pipeinstallations of the prior art. Drain pipe suitable for boreholeinstallation, such as, for example, perforated HDPE pipe, is far morerobust than the relatively thin walled perforated drain pipe of theprior art.

Also, in the prior art, the more robust HDPE pipe was used onlytemporarily to protect a relatively fragile drain pipe structure duringinstallation of the relatively fragile drain pipe. Then,post-installation, the protective HDPE pipe had to be removed. Accordingto the new system and method described herein, the more robust drainpipe (e.g. HDPE pipe) as provided with openings and/or holes becomes thepermanently installed drain pipe which is further protected by thepermanently installed permeable protective sock. In typicalinstallations, both the drain pipe and the permeable protective sock arepermanently and simultaneously installed in an underground opening orhole (e.g. pulled into a borehole). There is no longer any need for thetemporary protective outer pipe of the prior art, which must be removedpost-installation.

The fluid permeable sock offers a number of advantages over the priorart techniques for installing drain pipe. Particularly in hazardousenvironments, such sock materials as described hereinabove, however, nowwoven to be intentionally fluid permeable and provided without waterproof coating, are still resistant to deterioration by chemicalexposure. The materials are also strong and can protect the drain pipebefore, during, and after the installation of the drain pipe. In mostcases, the protection will last for the service life of the drain pipe.Also, as before, and for all of the aforementioned reasons, a drain pipecan also in some installations remain slidingly engaged or somewhatslidingly engaged, even with an intentionally permeable sock. Thus, itcan be seen that horizontal directional drilling can now be moreefficiently used to install a drain pipe (e.g. perforated drainage pipe)using such permeable sock materials as permeable woven ultra-highmolecular weight polyethylene or trampoline fabrics (not coated) so thatthe protective sock sleeve is water permeable and further can act as afilter to keep sediment and/or rocks and other debris from migratinginto the protected drain pipe.

While the present invention has been particularly shown and describedwith reference to the preferred mode as illustrated in the drawing, itwill be understood by one skilled in the art that various changes indetail may be affected therein without departing from the spirit andscope of the invention as defined by the claims. Moreover, where variousembodiments may have been described with particular reference to usewith respect to directional drilling, persons of ordinary skill in theart would understand that such embodiments would be substantiallyanalogous to use with respect to host pipe insertion, and vice versa.

In addition to directional drilling and host pipe insertion discussedabove, the techniques described hereinbelow are also applicable to augerboring, pipe ramming, static plowing, and any combinations thereof.

During development of the sock described in METHOD AND APPARATUS FORPROTECTING PIPE INSTALLED UNDERGROUND AFTER HORIZONTAL DRILLING as citedhereinabove, it was realized that such damage near the coupler is oftencaused by an angular deflection of the pipe near the installationapparatus connection to the pipe being inserted into the borehole (e.g.near a pull head). The reason for the angular deflection near the end ofthe pipe being inserted into the borehole is believed to be buoyancy ofan air filled pipe in any water and/or drilling slurry fluid in theborehole. Once the problem of pipe buoyancy was understood, a new methodof placing the coupler apparatus some distance from the end of the pipewas developed. In further testing, the coupler was typically placed morethan about six inches, preferably about two feet or more back from theend of the pipe being pulled into a borehole by an installationapparatus. Since the method was improved, there have no furtherinstances of damage to either the sock or one or more tracer wires beingsimultaneously pulled into a borehole. Effective distances for thecoupler from the end of the pipe can range from about half a foot (sixinches) to several feet depending on the type of pipe, the diameter ofthe pipe and the conditions in the borehole. For example, for poly pipesof about two or three inches in diameter, about a two feet distancebetween the end of a pipe and the coupler apparatus has been found tosubstantially eliminate any damage to any item being carried by acoupler.

What is claimed is:
 1. A perforated drain pipe protection apparatus in combination with a perforated drain pipe comprising: a perforated drain pipe having a plurality of perforations; a sheet of fluid permeable material woven from a plurality of high strength yarns having an inner surface and an outer surface and a longitudinal direction and a width direction defined by two edges of said sheet along said longitudinal direction; a fastening structure configured to join said two edges to form a seam as said sheet of permeable material is wrapped in said width direction around a perforated drain pipe to be installed underground to form a protective sock cover along said longitudinal direction, said sock configured to be installed underground with said perforated drain pipe about which it is wrapped; a coupler comprising a first coupler half and a second coupler half, both halves comprising a leading edge to stabilize a soil matrix as said pipe and said protective sock cover are inserted into a borehole, and at least one slot disposed in an outer surface to allow a fluid to pass by said coupler as said coupler is pulled through said borehole; a plurality of bolts to join said first coupler half to said second coupler half about said pipe and said protective sock cover, wherein said coupler formed by said first coupler half joined to said second coupler captures said protective sock cover at a location on said pipe at a distance of greater than about six inches from a first end of the pipe which is to be mechanically coupled to an installation apparatus to install the pipe and protective sock cover into the borehole, and wherein the installation apparatus is not directly coupled to said coupler for the installation of said pipe with said protective sock cover into said borehole; and wherein said protective sock cover acts as a fluid permeable filter which keeps debris including sediment or rocks from migrating into said perforated drain pipe while allowing fluid to drain from said perforated drain pipe through said plurality of perforations both during installation, and during a service life of said perforated drain pipe and said sock.
 2. The drain pipe protection apparatus of claim 1, wherein said drain pipe protection apparatus is configured to be installed into a borehole formed by a method selected from the group consisting of directional drilling, auger boring, pipe ramming, static plowing, and combinations thereof.
 3. The drain pipe protection apparatus of claim 1, wherein said pipe protection apparatus is configured to be inserted into a host drain pipe.
 4. The drain pipe protection apparatus of claim 1, wherein said sheet of permeable material comprises a long chain polyethylene.
 5. The drain pipe protection apparatus of claim 1, wherein said sheet of permeable material comprises an ultra-high density polyethylene.
 6. The drain pipe protection apparatus of claim 1, wherein said sheet of permeable material comprises an aramid.
 7. The drain pipe protection apparatus of claim 1, wherein said sheet of permeable material comprises a liquid crystal polymer.
 8. The drain pipe protection apparatus of claim 1, wherein said sheet of permeable material comprises a combination of one or more materials selected from the group consisting of a long chain polyethylene, an ultra-high density polyethylene, an aramid, and a liquid crystal polymer.
 9. The drain pipe protection apparatus of claim 1, wherein said sheet of permeable material comprises a woven polypropylene loaded with carbon.
 10. The drain pipe protection apparatus of claim 1, wherein said fastening structure comprises a hook-and-loop fastener.
 11. The drain pipe protection apparatus of claim 1, wherein said fastening structure comprises a zipper.
 12. The drain pipe protection apparatus of claim 1, wherein said permeable material comprises a high strength yarn.
 13. The drain pipe protection apparatus of claim 1, wherein said permeable material comprises a yarn formed from fibers having a tensile modulus equal to or greater than 150 grams/denier.
 14. The drain pipe protection apparatus of claim 1, further comprising a tracer wire.
 15. The drain pipe protection apparatus of claim 14, wherein said tracer wire is disposed within said fastener structure.
 16. A method for protecting a drain pipe before, during and after installation, comprising the steps of: providing a perforated drain pipe having a plurality of perforations and a sheet of permeable sock fabric comprising a sheet of fluid permeable material woven from a plurality of high strength yarns having an inner surface and an outer surface and a longitudinal direction and a width direction defined by two edges of said sheet along said longitudinal direction, a fastening structure configured to join said two edges to form a seam as said sheet of permeable material is wrapped in said width direction around a perforated drain pipe configured to be installed underground to form a protective sock cover along said longitudinal direction, and a clamp comprising a first coupler half and a second coupler half, both halves comprising a leading edge to stabilize a soil matrix as said pipe and said protective sock cover are inserted into a borehole, and at least one slot disposed in an outer surface to allow a fluid to pass by said coupler as said coupler is pulled through said borehole, a plurality of bolts to join said first coupler half to said second coupler half about said pipe and said protective sock cover, wherein said coupler formed by said first coupler half joined to said second coupler captures said protective sock cover at a location on said pipe at a distance of greater than about six inches from a first end of the pipe which is to be mechanically coupled to an installation apparatus to install the pipe and protective sock cover into the borehole, and wherein the installation apparatus is not directly coupled to said coupler for the installation of said pipe with said protective sock cover into said borehole, said sock configured to be installed underground with said perforated drain pipe about which it is wrapped, and wherein said protective sock cover acts as a fluid permeable filter which keeps debris including sediment or rocks from migrating into said perforated drain pipe while allowing fluid to drain from said perforated drain pipe through said plurality of perforations both during installation, and during a service life of said perforated drain pipe and said sock; installing said sheet of permeable sock fabric around said pipe by the steps of: placing said sheet of permeable sock fabric adjacent said drain pipe; wrapping said sheet of permeable sock fabric around said drain pipe; securing said sheet to itself along a seam to form a permeable sock-covered drain pipe; clamping said permeable sock to said pipe with said clamp; and installing said permeable sock-covered drain pipe underground.
 17. The method for protecting drain pipe of claim 16 wherein the step of installing said permeable sock-covered pipe underground further comprises inserting said permeable sock-covered pipe into a borehole.
 18. The method for protecting drain pipe of claim 17, wherein the borehole is formed by a method selected from the group consisting of directional drilling, auger boring, pipe ramming, static plowing, and combinations thereof.
 19. The method for protecting drain pipe of claim 18, wherein the step of installing said permeable sock-covered drain pipe underground further comprises inserting said permeable sock-covered drain pipe into a host drain pipe.
 20. The method for protecting drain pipe of claim 16, wherein said step of providing said sheet of permeable sock fabric comprises providing a roll of said sheet of permeable sock fabric.
 21. The method for protecting drain pipe of claim 20, wherein said step of providing said sheet of permeable sock fabric comprises providing said sheet of permeable sock fabric comprising a material selected from the group consisting of a long chain polyethylene, an ultra-high density polyethylene, an aramid, a liquid crystal polymer, and combinations thereof. 